Yes, I broke my own rules and used a "breaking" modifier for this story (let me have my fun for once). Here we have it, as the rumour mill suggested, Google has released the On2 VP8 video codec as open source (royalty free, BSD-style), while also launching the WebM container format which combines a VP8 video stream with Vorbis audio. Support for WebM has been enabled on YouTube's HTML5 beta, and you can download patches against ffmpeg as well as DirectShow filters for Windows (Gstreamer plugins are labelled as "coming soon"). Mac users are out of luck for now; no QuickTime plugins have been announced yet. Update: The WebM blog is now open - and the list of partners is pretty decent already. It includes ARM, NVIDIA, AMD, Qualcomm, and many others. Update II: VP8 will be baked into Flash. Update III: The Opera labs version with WebM support has been released too, for Linux, Mac, and Windows.

I realize that, but being a subset, WebM itself defines a container that is wholly compatible with Matroska, so any device, software or platform that can understand VP8, MKV, and Vorbis should already be able to play WebM without needing any specific support for it. A number of household media player devices can already play MKV and Vorbis for example.

In other words, WebM itself doesn't define anything not already defined by something else. What's new is VP8, not WebM. If you really need another name to call it, perhaps something like mkm or mkx, etc would've been more appropriate. Again just an opinion, that should not detract from the good news about VP8 in general.